Organic electroluminescent compound and organic electroluminescent device comprising the same

ABSTRACT

The present disclosure relates to an organic electroluminescent compound and an organic electroluminescent device comprising the same. By using the organic electroluminescent compound according to the present disclosure, it is possible to produce an organic electroluminescent device which has a low driving voltage, excellent current and power efficiencies, and improved operation lifespan.

TECHNICAL FIELD

The present disclosure relates to an organic electroluminescent compoundand an organic electroluminescent device comprising the same.

BACKGROUND ART

An electroluminescent (EL) device is a self-light-emitting device whichhas advantages in that it provides a wider viewing angle, a greatercontrast ratio, and a faster response time. An organic EL device wasfirst developed by Eastman Kodak, by using small aromatic diaminemolecules and aluminum complexes as materials to form a light-emittinglayer [Appl. Phys. Lett. 51, 913, 1987].

The most important factor determining luminous efficiency in the organicEL device is light-emitting materials. Until now, fluorescent materialshave been widely used as light-emitting material. However, in view ofelectroluminescent mechanisms, since phosphorescent materialstheoretically enhance luminous efficiency by four (4) times compared tofluorescent materials, phosphorescent light-emitting materials have beenwidely researched. Iridium(III) complexes have been widely known asphosphorescent materials, includingbis(2-(2′-benzothienyl)-pyridinato-N,C-3′)iridium(acetylacetonate)((acac)Ir(btp)₂), tris(2-phenylpyridine)iridium (Ir(ppy)₃) andbis(4,6-difluorophenylpyridinato-N,C2)picolinate iridium (Firpic) asred-, green-, and blue-emitting materials, respectively.

At present, 4,4′-N,N′-dicarbazol-biphenyl (CBP) is the most widely knownhost material for phosphorescent materials. Recently, Pioneer (Japan) etal., developed a high performance organic EL device using bathocuproine(BCP) and aluminum(III) bis(2-methyl-8-quinolinate)(4-phenylphenolate)(BAlq) etc., as host materials, which were known as hole blockingmaterials.

Although these materials provide good luminous characteristics, theyhave the following disadvantages: (1) Due to their low glass transitiontemperature and poor thermal stability, their degradation may occurduring a high-temperature deposition process in a vacuum, which resultsin poor lifespan. (2) The power efficiency of the organic EL device isgiven by [(π/voltage)×current efficiency], and the power efficiency isinversely proportional to the voltage. Although the organic EL devicecomprising phosphorescent host materials provides higher currentefficiency (cd/A) than one comprising fluorescent materials, asignificantly high driving voltage is necessary. Thus, there is no meritin terms of power efficiency (lm/W). (3) Furthermore, the operationallifespan of the organic EL device is short, and luminous efficiency isstill required to be improved.

Korean Patent No. 955993 discloses an indolocarbazole derivativesubstituted with a nitrogen-containing heterocycle. However, it fails todisclose an indolocarbazole derivative fused with a benzofuran orbenzothiophene.

DISCLOSURE OF THE INVENTION Problems to be Solved

The objective of the present disclosure is to provide an organicelectroluminescent compound, which can provide an organicelectroluminescent device showing long lifespan, low driving voltage,and good luminos efficiency such as current and power efficiencies, andan organic electroluminescent device comprising the same.

Solution to Problems

The present inventors found that the above objective can be achieved byan organic electroluminescent compound represented by the followingformula 1.

wherein

X represents —O— or —S—;

R₁ to R₆, each independently, represent hydrogen, deuterium, a halogen,a cyano, a substituted or unsubstituted (C1-C30)alkyl, a substituted orunsubstituted (C6-C30)aryl, a substituted or unsubstituted (3- to30-membered)heteroaryl, a substituted or unsubstituted(C3-C30)cycloalkyl, a substituted or unsubstituted (C1-C30)alkoxy, asubstituted or unsubstituted tri(C1-C30)alkylsilyl, a substituted orunsubstituted di(C1-C30)alkyl(C6-C30)arylsilyl, a substituted orunsubstituted (C1-C30)alkyldi(C6-C30)arylsilyl, a substituted orunsubstituted tri(C6-C30)arylsilyl, a substituted or unsubstituted mono-or di-(C1-C30)alkylamino, a substituted or unsubstituted mono- ordi-(C6-C30)arylamino, or a substituted or unsubstituted(C1-C30)alkyl(C6-C30)arylamino; or may be linked to an adjacentsubstituent(s) to form a (3- to 30-membered), mono- or polycyclic,alicyclic or aromatic ring whose carbon atom(s) may be replaced with atleast one hetero atom selected from nitrogen, oxygen, and sulfur; and

the heteroaryl contains at least one hetero atom selected from B, N, O,S, Si, and P.

Effects of the Invention

The organic electroluminescent compound of the present disclosure canprovide an organic electroluminescent device having a low drivingvoltage, excellent current and power efficiencies, and remarkablyimproved operation lifespan.

EMBODIMENTS OF THE INVENTION

Hereinafter, the present disclosure will be described in detail.However, the following description is intended to explain the invention,and is not meant in any way to restrict the scope of the invention.

The present disclosure provides the organic electroluminescent compoundof formula 1 above, an organic electroluminescent material comprisingthe organic electroluminescent compound, and an organicelectroluminescent device comprising the organic electroluminescentcompound.

The details of the organic electroluminescent compound of formula 1 areas follows.

Herein, “alkyl” includes methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, tert-butyl, etc. “Cycloalkyl” includes cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, etc. “(3- to7-membered)heterocycloalkyl” indicates a cycloalkyl having 3 to 7 ringbackbone atoms including at least one hetero atom selected from B, N, O,S, Si, and P, preferably O, S, and N, and includes tetrahydrofuran,pyrrolidine, thiolan, tetrahydropyran, etc. Furthermore, “aryl(ene)”indicates a monocyclic or fused ring derived from an aromatichydrocarbon, and includes a spiro compound in which two rings areconnected through one atom. The aryl includes phenyl, biphenyl,terphenyl, naphthyl, binaphthyl, phenylnaphthyl, naphthylphenyl,fluorenyl, phenylfluorenyl, benzofluorenyl, dibenzofluorenyl,phenanthrenyl, phenylphenanthrenyl, anthracenyl, indenyl, triphenylenyl,pyrenyl, tetracenyl, perylenyl, chrysenyl, naphthacenyl, fluoranthenyl,spirobifluorenyl, etc. “(3- to 30-membered)heteroaryl(ene)” indicates anaryl group having 3 to 30 ring backbone atoms including at least one,preferably 1 to 4, hetero atom selected from the group consisting of B,N, O, S, Si, and P, preferably O, S, and N; may be a monocyclic ring, ora fused ring condensed with at least one benzene ring; may be partiallysaturated; may be one formed by linking at least one heteroaryl or arylgroup to a heteroaryl group via a single bond(s); and includes amonocyclic ring-type heteroaryl such as furyl, thiophenyl, pyrrolyl,imidazolyl, pyrazolyl, thiazolyl, thiadiazolyl, isothiazolyl,isoxazolyl, oxazolyl, oxadiazolyl, triazinyl, tetrazinyl, triazolyl,tetrazolyl, furazanyl, pyridyl, pyrazinyl, pyrimidyl, pyridazinyl, etc.,and a fused ring-type heteroaryl such as benzofuranyl, benzothiophenyl,isobenzofuranyl, dibenzofuranyl, dibenzothiophenyl, benzoimidazolyl,benzothiazolyl, benzoisothiazolyl, benzoisoxazolyl, benzoxazolyl,isoindolyl, indolyl, indazolyl, benzothiadiazolyl, quinolyl,isoquinolyl, cinnolinyl, quinazolinyl, quinoxalinyl, carbazolyl,phenoxazinyl, phenanthridinyl, benzodioxolyl, dihydroacridinyl, etc.Furthermore, “halogen” includes F, Cl, Br, and I.

Herein, “substituted” in the expression, “substituted or unsubstituted,”means that a hydrogen atom in a certain functional group is replacedwith another atom or group, i.e. a substituent. The substituents for thesubstituted alkyl, the substituted aryl(ene), the substitutedheteroaryl(ene), the substituted cycloalkyl, the substituted alkoxy, thesubstituted trialkylsilyl, the substituted dialkylarylsilyl, thesubstituted alkyldiarylsilyl, the substituted triarylsilyl, thesubstituted mono- or di-alkylamino, the substituted mono- ordi-arylamino, the substituted alkylarylamino, and the substituted mono-or polycyclic, alicyclic or aromatic ring of R₁ to R₆, L₁, L₂, A₁, A₂,M, L₄, L, Y₁, Y₂, R₂₁ to R₂₇, R₃₁ to R₃₃, R₁₀₀ to R₁₀₉, R₁₁₁ to R₁₂₇,and R₂₀₁ to R₂₁₁, each independently, are at least one selected from thegroup consisting of deuterium, a halogen, a cyano, a carboxy, a nitro, ahydroxy, a (C1-C30)alkyl, a halo(C1-C30)alkyl, a (C1-C30)alkoxy, a(C1-C30)alkylthio, a (C3-C30)cycloalkyl, a 3- to 7-memberedheterocycloalkyl, a (C6-C30)aryloxy, a (C6-C30)arylthio, a 3- to30-membered heteroaryl unsubstituted or substituted with a (C6-C30)arylor a di(C6-C30)arylamino, a (C6-C30)aryl unsubstituted or substitutedwith a 3- to 30-membered heteroaryl or a di(C6-C30)arylamino, atri(C1-C30)alkylsilyl, a tri(C6-C30)arylsilyl, adi(C1-C30)alkyl(C6-C30)arylsilyl, a (C1-C30)alkyldi(C6-C30)arylsilyl, anamino, a mono- or di-(C1-C30)alkylamino, a mono- ordi-(C6-C30)arylamino, a (C1-C30)alkyl(C6-C30)arylamino, a(C1-C30)alkylcarbonyl, a (C1-C30)alkoxycarbonyl, a (C6-C30)arylcarbonyl,a di(C6-C30)arylboronyl, a di(C1-C30)alkylboronyl, a(C1-C30)alkyl(C6-C30)arylboronyl, a (C6-C30)aryl(C1-C30)alkyl, and a(C1-C30)alkyl(C6-C30)aryl.

Specifically, the compound represented by formula 1 may be representedby any one of the following formulae 2 to 7; and more specifically, maybe represented by formula 2 or 7.

wherein X, and R₁ to R₆ are as defined in formula 1.

Specifically, R₁ and R₂, each independently, may represent hydrogen, asubstituted or unsubstituted (C6-C30)aryl, or a substituted orunsubstituted 5- to 30-membered heteroaryl. More specifically, R₁ may behydrogen or the group represented by the following formula 8; and R₂ maybe hydrogen, or the group represented by the following formula 9.*-L₁-Ar₁  (8)*-L₂-Ar₂  (9)

wherein

L₁ and L₂, each independently, represent a single bond, a substituted orunsubstituted (C6-C30)arylene, or a substituted or unsubstituted 3- to30-membered heteroarylene;

Ar₁ and Ar₂, each independently, represent a substituted orunsubstituted (C6-C30)aryl, or a substituted or unsubstituted 3- to30-membered heteroaryl;

the heteroaryl contains at least one hetero atom selected from B, N, O,S, Si, and P; and

* represents a bonding site.

Specifically, L₁ and L₂, each independently, may represent a singlebond, or a substituted or unsubstituted (C6-C20)arylene. Morespecifically, L₁ and L₂, each independently, may represent a singlebond, a substituted or unsubstituted phenylene, a substituted orunsubstituted biphenylene, a substituted or unsubstituted terphenylene,a substituted or unsubstituted naphthylene, a substituted orunsubstituted binaphthylene, a substituted or unsubstitutedphenanthrenylene, a substituted or unsubstituted anthracenylene, asubstituted or unsubstituted triphenylenylene, a substituted orunsubstituted fluoranthenylene, a substituted or unsubstitutedpyrenylene, a substituted or unsubstituted tetracenylene, a substitutedor unsubstituted perylenylene, a substituted or unsubstitutedchrysenylene, or a substituted or unsubstituted fluorenylene.

Specifically, Ar₁ and Ar₂, each independently, may represent asubstituted or unsubstituted (C6-C20)aryl; or a substituted orunsubstituted nitrogen-containing 5- to 20-membered heteroaryl. Morespecifically, Ar₁ and Ar₂, each independently, may represent asubstituted or unsubstituted phenyl, a substituted or unsubstitutedbiphenyl, a substituted or unsubstituted terphenyl, a substituted orunsubstituted naphthyl, a substituted or unsubstituted binaphthyl, asubstituted or unsubstituted phenanthrenyl, a substituted orunsubstituted anthracenyl, a substituted or unsubstituted triphenylenyl,a substituted or unsubstituted fluoranthenyl, a substituted orunsubstituted pyrenyl, a substituted or unsubstituted tetracenyl, asubstituted or unsubstituted perylenyl, or a substituted orunsubstituted chrysenyl, a substituted or unsubstituted fluorenyl, asubstituted or unsubstituted benzofluorenyl, a substituted orunsubstituted dibenzofluorenyl, a substituted or unsubstituted pyridyl,a substituted or unsubstituted pyrazinyl, a substituted or unsubstitutedpyrimidyl, a substituted or unsubstituted pyridazinyl, a substituted orunsubstituted triazinyl, a substituted or unsubstituted quinolyl, asubstituted or unsubstituted isoquinolyl, a substituted or unsubstitutedcinnolinyl, a substituted or unsubstituted quinazolinyl, a substitutedor unsubstituted quinoxalinyl, or a substituted or unsubstitutedphthalazinyl. Specifically, the substituent of the substituted group ofAr₁ and Ar₂, each independently, may be selected from the groupconsisting of a (C1-C10)alkyl, a (C6-C20)aryl, and a 5- to 20-memberedheteroaryl.

More specifically, the group represented by formula 8 and the grouprepresented by formula 9, each independently, may be selected from thefollowing.

Specifically, R₃ to R₆, each independently, may represent hydrogen,deuterium, a halogen, a cyano, a substituted or unsubstituted(C1-C10)alkyl, a substituted or unsubstituted (C6-C18)aryl, or asubstituted or unsubstituted 5- to 18-membered heteroaryl, or may belinked to an adjacent substituent(s) to form a mono- or polycyclic 5- to18-membered aromatic ring whose carbon atom(s) may be replaced with atleast one hetero atom selected from nitrogen, oxygen, and sulfur. Morespecifically, R₃ to R₆, each independently, may represent hydrogen, asubstituted or unsubstituted (C6-C18)aryl, or a substituted orunsubstituted 5- to 18-membered heteroaryl, or may be linked to anadjacent substituent(s) to form a mono- or polycyclic 5- to 18-memberedaromatic ring.

More specifically, the organic electroluminescent compound of thepresent disclosure includes the following, but is not limited thereto:

The organic electroluminescent compound of the present disclosure can beprepared by a synthetic method known to one skilled in the art. Forexample, it can be prepared according to the following reaction scheme1.

Furthermore, the present disclosure provides an organicelectroluminescent material comprising the organic electroluminescentcompound of formula 1, and an organic electroluminescent devicecomprising the material.

The material may consist of the organic electroluminescent compound ofthe present disclosure. Otherwise, the material may further comprise aconventional compound(s) which has been comprised for an organicelectroluminescent material.

The organic electroluminescent material may be preferably, a hostmaterial, or a hole transport material. The host material may be afluorescent host material or a phosphorescent host material, andspecifically a phosphorescent host material. Where the organicelectroluminescent material is used as a host material, it may furthercomprise, in addition to the compound of formula 1, a second hostmaterial mentioned below.

The organic electroluminescent device of the present disclosure maycomprise a first electrode, a second electrode, and at least one organiclayer disposed between the first and second electrodes. The organiclayer may comprise at least one compound of formula 1.

One of the first and second electrodes may be an anode, and the othermay be a cathode. The organic layer may comprise a light-emitting layer,and may further comprise at least one layer selected from a holeinjection layer, a hole transport layer, an electron transport layer, anelectron injection layer, an interlayer, a hole blocking layer, anelectron blocking layer, and an electron buffer layer.

The organic electroluminescent compound of the present disclosure may becomprised in at least one of the light-emitting layer and the holetransport layer. When used in the hole transport layer, the organicelectroluminescent compound of the present disclosure may be comprisedas a hole transport material. When the compound of the presentdisclosure is used in the hole transport layer, the light-emitting layermay comprise a fluorescent host material or phosphorescent host materialas a host material, wherein the host material may be selected from thewell-known materials, and may be identical with or different from thematerial used in the hole transport layer. When used in thelight-emitting layer, the compound of the present disclosure may becomprised as a host material, and specifically as a phosphorescent hostmaterial. Preferably, the light-emitting layer may further comprise atleast one or more dopants, and, if necessary, a second host materialother than the compound of formula 1 of the present disclosure. It ispreferable that a doping amount of the dopant compound is less than 20wt % based on the total amount of the host compound and the dopantcompound in a light-emitting layer. The weight ratio in thelight-emitting layer between the first host material and the second hostmaterial is in the range of 1:99 to 99:1, and specifically 30:70 to70:30 in view of driving voltage, luminous efficiency, and lifespan.

The second host material may be from any of the known phosphorescenthost materials. The material selected from the group consisting of thecompounds of formulae 10 to 14 below is preferable as the second hostmaterial in view of luminous efficiency.

Wherein, Cz represents the following structure:

A represents —O— or —S—; R₂₁ to R₂₄, each independently, representhydrogen, deuterium, a halogen, a substituted or unsubstituted(C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, asubstituted or unsubstituted 5- to 30-membered heteroaryl orR₂₅R₂₆R₂₇Si—; R₂₅ to R₂₇, each independently, represent a substituted orunsubstituted (C1-C30)alkyl, or a substituted or unsubstituted(C6-C30)aryl; L₄ represents a single bond, a substituted orunsubstituted (C6-C30)arylene, or a substituted or unsubstituted 5- to30-membered heteroarylene; M represents a substituted or unsubstituted(C6-C30)aryl, or a substituted or unsubstituted 5- to 30-memberedheteroaryl; Y₁ and Y₂, each independently, represent —O—, —S—, —N(R₃₁)—,or —C(R₃₂)(R₃₃)—, and Y₁ and Y₂ are not present simultaneously; R₃₁ toR₃₃, each independently, represent a substituted or unsubstituted(C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, or asubstituted or unsubstituted 5- to 30-membered heteroaryl, R₃₂ and R₃₃may be the same or different; h and i, each independently, represent aninteger of 1 to 3; j, k, l and m each independently, represent aninteger of 0 to 4; and where h, i, j, k, l or m is an integer of 2 ormore, each of (Cz-L₄), (Cz), R₂₁, R₂₂, R₂₃, or R₂₄ may be the same ordifferent.

Specifically, the preferable examples of the second host materialinclude the following:

(wherein, TPS represents triphenylsilyl.)

The dopant is preferably at least one phosphorescent dopant. Thephosphorescent dopant material for the organic electroluminescent deviceof the present disclosure is not limited, but may be preferably selectedfrom metallated complex compounds of iridium (Ir), osmium (Os), copper(Cu) or platinum (Pt), more preferably selected from ortho-metallatedcomplex compounds of iridium (Ir), osmium (Os), copper (Cu) or platinum(Pt), and even more preferably ortho-metallated iridium complexcompounds.

The dopant to be comprised in the organic electroluminescent device ofthe present disclosure may be selected from the group consisting ofcompounds represented by the following formulae 15 to 17.

wherein L is selected from the following structures:

R₁₀₀ represents hydrogen, a substituted or unsubstituted (C1-C30)alkyl,or a substituted or unsubstituted (C3-C30)cycloalkyl; R₁₀₁ to R₁₀₃ andR₁₁₁ to R₁₂₃, each independently, represent hydrogen, deuterium, ahalogen, a (C1-C30)alkyl unsubstituted or substituted with a halogen, asubstituted or unsubstituted (C3-C30)cycloalkyl, a cyano, or asubstituted or unsubstituted (C1-C30)alkoxy; R₁₀₆ to R₁₀₃ may be linkedto an adjacent substituent(s) to form a substituted or unsubstitutedfused ring, for example, a substituted or unsubstituted fluorene, asubstituted or unsubstituted dibenzothiophene, or a substituted orunsubstituted dibenzofuran; R₁₂₀ to R₁₂₃ may be linked to an adjacentsubstituent(s) to form a substituted or unsubstituted fused ring, forexample, a substituted or unsubstituted quinoline; R₁₂₄ to R₁₂₇, eachindependently, represent hydrogen, deuterium, a halogen, a substitutedor unsubstituted (C1-C30)alkyl, or a substituted or unsubstituted(C1-C30)aryl; where any of R₁₂₄ to R₁₂₇ is aryl, it may be linked to anadjacent substituent(s) to form a substituted or unsubstituted fusedring, for example, a substituted or unsubstituted fluorene, asubstituted or unsubstituted dibenzofuran, or a substituted orunsubstituted dibenzothiophene; R₂₀₁ to R₂₁₁, each independently,represent hydrogen, deuterium, a halogen, a (C1-C30)alkyl unsubstitutedor substituted with a halogen, a substituted or unsubstituted(C3-C30)cycloalkyl, or a substituted or unsubstituted (C6-C30)aryl; anyof R₂₀₈ to R₂₁₁ may be linked to an adjacent substituent(s) to form asubstituted or unsubstituted fused ring, for example, a substituted orunsubstituted fluorene, a substituted or unsubstituted dibenzothiophene,or a substituted or unsubstituted dibenzofuran; f and g, eachindependently, represent an integer of 1 to 3; where f or g is aninteger of 2 or more, each of R₁₀₀ may be the same or different; and nrepresents an integer of 1 to 3.

Specifically, the dopant material includes the following:

According to an additional aspect of the present disclosure, a mixtureor composition for preparing an organic electroluminescent device isprovided. The mixture or composition comprises the compound of thepresent disclosure. The mixture or composition may be used for preparinga light-emitting layer or hole transport layer of the organicelectroluminescent device. The mixture or composition may be used forpreparing a phosphorescent or fluorescent light-emitting layer, andspecifically a red-emitting phosphorescent light-emitting layer of theorganic electroluminescent device. When comprised in the mixture orcomposition for preparing a hole transport layer of the organicelectroluminescent device, the compound of the present disclosure may becomprised as a hole transport material. When comprised in the mixture orcomposition for preparing a light-emitting layer of the organicelectroluminescent device, the compound of the present disclosure may becomprised as a host material. When comprised as a host material, themixture or composition may further comprise a second host material. Theweight ratio between the first host material and the second hostmaterial is in the range of 1:99 to 99:1.

The organic electroluminescent device of the present disclosure maycomprise a first electrode, a second electrode, and at least one organiclayer disposed between the first and second electrodes, wherein theorganic layer may comprise the mixture or composition for preparing anorganic electroluminescent device of the present disclosure.

The organic electroluminescent device of the present disclosure mayfurther comprise, in addition to the compound of formula 1, at least onecompound selected from the group consisting of arylamine-based compoundsand styrylarylamine-based compounds.

In the organic electroluminescent device of the present disclosure, theorganic layer may further comprise, in addition to the compound offormula 1, at least one metal selected from the group consisting ofmetals of Group 1, metals of Group 2, transition metals of the 4^(th)period, transition metals of the 5^(th) period, lanthanides and organicmetals of the d-transition elements of the Periodic Table, or at leastone complex compound comprising the metal. The organic layer may furthercomprise a light-emitting layer and a charge generating layer.

In addition, the organic electroluminescent device of the presentdisclosure may emit white light by further comprising at least onelight-emitting layer, which comprises a blue electroluminescentcompound, a red electroluminescent compound or a greenelectroluminescent compound known in the art, besides the compound ofthe present disclosure.

In the organic electroluminescent device of the present disclosure,preferably, at least one layer (hereinafter, “a surface layer”) may beplaced on an inner surface(s) of one or both electrode(s), selected froma chalcogenide layer, a metal halide layer and a metal oxide layer.Specifically, a chalcogenide (includes oxides) layer of silicon oraluminum is preferably placed on an anode surface of anelectroluminescent medium layer, and a metal halide layer or a metaloxide layer is preferably placed on a cathode surface of anelectroluminescent medium layer. Such a surface layer provides operationstability for the organic electroluminescent device. Preferably, thechalcogenide includes SiO_(x)(1≤X≤2), AlO_(x)(1≤X≤1.5), SiON, SiAlON,etc.; the metal halide includes LiF, MgF₂, CaF₂, a rare earth metalfluoride, etc.; and the metal oxide includes Cs₂O, Li₂O, MgO, SrO, BaO,CaO, etc.

In the organic electroluminescent device of the present disclosure, amixed region of an electron transport compound and a reductive dopant,or a mixed region of a hole transport compound and an oxidative dopantmay be placed on at least one surface of a pair of electrodes. In thiscase, the electron transport compound is reduced to an anion, and thusit becomes easier to inject and transport electrons from the mixedregion to an electroluminescent medium. Furthermore, the hole transportcompound is oxidized to a cation, and thus it becomes easier to injectand transport holes from the mixed region to the electroluminescentmedium. Preferably, the oxidative dopant includes various Lewis acidsand acceptor compounds, and the reductive dopant includes alkali metals,alkali metal compounds, alkaline earth metals, rare-earth metals, andmixtures thereof. A reductive dopant layer may be employed as a chargegenerating layer to prepare an electroluminescent device having two ormore light-emitting layers and emitting white light.

In order to form each layer of the organic electroluminescent device ofthe present disclosure, dry film-forming methods such as vacuumevaporation, sputtering, plasma and ion plating methods, or wetfilm-forming methods such as spin coating, dip coating, and flow coatingmethods can be used.

When using a wet film-forming method, a thin film can be formed bydissolving or diffusing materials forming each layer into any suitablesolvent such as ethanol, chloroform, tetrahydrofuran, dioxane, etc. Thesolvent can be any solvent where the materials forming each layer can bedissolved or diffused, and where there are no problems in film-formationcapability.

Hereinafter, the organic electroluminescent compound of the presentdisclosure, the preparation method of the compound, and the luminescentproperties of the device will be explained in detail with reference tothe following examples.

Example 1: Preparation of Compound A-53

1) Preparation of Compound 1

After introducing dibenzofuran-4-boronic acid (35 g, 165 mmol),2,5-dibromo-nitrobenzene (55.6 g, 198 mmol),tetrakis(triphenylphosphine)palladium (Pd(PPh₃)₄) (7.6 g, 6.6 mmol),Na₂CO₃ (43.7 g, 413 mmol), toluene (800 mL), ethanol (100 mL), and water(200 mL) into a 2 L round-bottom flask, the mixture was stirred at 120°C. for 3.5 hours. A work-up of the reaction mixture was performed withethyl acetate (EA)/H₂O. The resultant was dried with MgSO₄, anddistilled under reduced pressure. The crude product was subjected tocolumn chromatography with methylene chloride (MC):Hexane to obtainyellow liquid of compound 1 (41 g, yield 67%).

2) Preparation of Compound 2

After introducing 4-(4-bromo-2-nitrophenyl)dibenzo[b,d]furan (41 g, 111mmol), triethylphosphite (370 mL), and 1,2-dichlorobenzene (1,2-DCB)(370 mL) into a 2 L round-bottom flask, the mixture was stirred at 150°C. for 4 hours. The reaction mixture was distilled under reducedpressure to obtain solids. The crude product was subjected to columnchromatography with MC:Hexane to obtain white solids of compound 2 (27.3g, yield 73%).

3) Preparation of Compound 3

After introducing 3-bromo-5H-benzofuro[3,2-c]carbazole (27.3 g, 81mmol), iodobenzene (22.7 mL, 203 mmol), CuI (23.2 g), ethylene diamine(16.4 mL), K₃PO₄ (34.5 g), and toluene (400 mL) into 1 L round-bottomflask, the mixture was stirred at 120° C. for 2.5 hours. A work-up ofthe reaction mixture was performed with EA/H₂O. The resultant was driedwith MgSO₄, and then distilled under reduced pressure. The crude productwas subjected to column chromatography with MC:Hexane to obtain whitesolids of compound 3 (20.6 g, yield 61%).

4) Preparation of Compound 4

After dissolving 3-bromo-5-phenyl-5H-benzofuro[3,2-c]carbazole (20.6 g,50 mmol), 2-chloroaniline (8 mL, 75 mmol), palladium(II) acetate(Pd(OAc)₂) (449 mg, 2 mmol), tri-tert-butylphosphine (P(t-Bu)₃) (2 mL, 4mmol), and sodium t-butoxide (NaOtBu) (12 g, 125 mmol) into toluene (250mL) in a 1 L round-bottom flask, the mixture was stirred at 130° C. for2.5 hours. A work-up of the reaction mixture was performed with EA/H₂O.The resultant was dried with MgSO₄, and then distilled under reducedpressure. The crude product was subjected to column chromatography withMC:Hexane to obtain white solids of compound 4 (18 g, yield 78%).

5) Preparation of Compound 5

After introducingN-(2-chlorophenyl)-5-phenyl-5H-benzofuro[3,2-c]carbazole-3-amine (18 g,39 mmol), palladium(II) acetate (Pd(OAc)₂) (440 mg, 1.96 mmol), ligand(1.4 g, 3.9 mmol), Cs₂CO₃ (38 g, 117 mmol), and dimethylacetylamide(DMA) (200 mL) into a 1 L round-bottom flask, the mixture was stirred at190° C. overnight. The reaction mixture was added dropwise back to waterto obtain solids. The crude products were subjected to columnchromatography with MC:Hexane to obtain white solids of compound 5 (7 g,yield 42%).

6) Preparation of Compound A-53

After introducing7-phenyl-7,9-dihydrobenzofuro[2,3-g]indolo[2,3-b]carbazole (6 g, 14.2mmol), 2-chloro-3-phenylquinoxaline (3.1 g, 12.9 mmol), NaH (60% in adispersion oil) (771 mg, 19.3 mmol), and dimethylformamide (DMF) (70 mL)into a 500 mL round-bottom flask, the mixture was stirred at 50° C. for5 hours. The reaction mixture was added dropwise back to water to obtainsolids. The crude products were subjected to column chromatography withMC:Hexane to obtain yellow solids of compound A-53 (1.8 g, yield 22%).

Molecular weight Melting point (MW) UV PL (M.P) A-53 627 344 nm 519 nm298° C.

Example 2: Preparation of Compound A-35

1) Preparation of Compound 1-1

After introducing compound A (80 g, 284.7 mmol), dibenzo[b,d]furan-4-ylboronic acid (51 g, 342 mmol), Pd(PPh₃)₄ (9.8 g, 8.54 mmol), 2M Na₂CO₃(5000 mL), toluene (1000 mL), purified water (500 mL), and ethanol (500mL) into a flask, the mixture was stirred under reflux for 5 hours.After completion of the reaction, the mixture was extracted with ethylacetate. The obtained organic layer was dried with magnesium sulfate toremove the remaining moisture, and then subjected to columnchromatography to obtain compound 1-1 (70 g, yield 67%).

2) Preparation of Compound 1-2

After dissolving compound 1-1 (70 g, 190 mmol), and triphenylphosphine(125 g, 475 mmol) into dichlorobenzene (1 L) of a flask, the mixture wasunder reflux at 150° C. for 6 hours. After completion of the reaction,the mixture was distilled and subjected to trituration with methanol(MeOH) to obtain compound 1-2 (41 g, yield 64%).

3) Preparation of Compound 1-3

After dissolving compound 1-2 (41 g, 120.77 mmol), iodobenzene (27 mL,241.54 mmol), CuI (12 g, 60.38 mmol), Cs₂CO₃ (118 g, 362 mmol), andethylene diamine (EDA) (4 mL, 60.38 mmol) into toluene (600 mL) in aflask, the mixture was under reflux at 120° C. for 5 hours. Aftercompletion of the reaction, the mixture was extracted with ethyl acetateand the obtained organic layer was dried with magnesium sulfate toremove the remaining moisture. The resultant was subjected to columnchromatography to obtain compound 1-3 (34 g, yield 67%).

4) Preparation of Compound 1-4

After dissolving compound 1-3 (34 g, 82.42 mmol), 2-chloroaniline (13mL, 123.70 mmol), Pd(OAc)₂ (0.7 g, 3.29 mmol), NaOtBu (19 g, 206 mmol),and P(t-Bu)₃ (3 mL, 6.59 mmol) into toluene (500 mL) in a flask, themixture was under reflux at 120° C. for 5 hours. After completion of thereaction, the mixture was extracted with ethyl acetate and the obtainedorganic layer was dried with magnesium sulfate to remove the remainingmoisture. The resultant was subjected to column chromatography to obtaincompound 1-4 (16.3 g, yield 47%).

5) Preparation of Compound 1-5

After dissolving compound 1-4 (15.3 g, 33.34 mmol), Pd(OAc)₂ (0.3 g,1.677 mmol), Cs₂CO₃ (32 g, 100.02 mmol), and ligand(tricyclohexylphosphine tetrafluoroborate) (PCy₃HBF₄) (1.2 g, 3.34 mmol)in N,N-dimethylacetylamide (170 mL) in a flask, the mixture was underreflux at 120° C. for 5 hours. After completion of the reaction, themixture was extracted with ethyl acetate and dried with magnesiumsulfate to remove the remaining moisture. The resultant was dried, andsubjected to column chromatography to obtain compound 1-5 (6 g, yield43%).

6) Preparation of Compound A-35

After dissolving compound 1-5 (6 g, 14 mmol), and compound B (4 g, 17mmol) into DMF (100 mL), NaH (0.8 g, 21 mmol, 60% in a mineral oil) wasadded thereto. The mixture was stirred at room temperature for 12 hours.Methanol and distilled water were added to the mixture. The mixture wasfiltered under reduced pressure, and the obtained solids were subjectedto column chromatography to obtain compound A-35 (4.5 g, yield 56%).

MW UV PL M.P A-35 626.70 356 nm 521 nm 274° C.

Example 3: Preparation of Compound A-6

1) Preparation of Compound 1-1

After introducing 2,5-dibromo-nitrobenzene (70 g, 249 mmol),4-dibenzofuran boronic acid (53 g, 249 mmol),tetrakis(triphenylphosphine)palladium (5.7 g, 4.98 mmol), sodiumcarbonate (53 g, 498 mmol), toluene (750 mL), and ethanol (250 mL) intoa reaction vessel, distilled water (250 mL) was added to the mixture.The mixture was stirred at 120° C. for 3 hours. After completion of thereaction, the mixture was washed with distilled water, and extractedwith ethyl acetate. The obtained organic layer was dried with magnesiumsulfate, and the solvent was removed by rotary evaporator. The resultantwas subjected to column chromatography to obtain compound 1-1 (60 g,yield 65%).

2) Preparation of Compound 1-3

After introducing compound 1-1 (60 g, 163 mmol), triethylphosphite (400mL), and o-dichlorobenzene (400 mL) into a reaction vessel, the mixturewas under reflux overnight. The reaction mixture was distilled underreduced pressure, and the solvent was removed therefrom to obtaincompound 1-2, which was used for the next reaction without furtherpurification. After adding iodobenzene (36 mL, 326 mmol), copper(I)iodide (15.5 g, 81.5 mmol), ethylene diamine (10 mL, 163 mmol), cesiumcarbonate (80 g, 245 mmol), and toluene (800 mL) to the reaction vesselcontaining compound 1-2, the mixture was stirred under reflux at 140° C.for 6 hours. After completion of the reaction, the mixture was washedwith distilled water and extracted with ethyl acetate. The obtainedorganic layer was dried with magnesium sulfate, and the solvent wasremoved by rotary evaporator. The resultant was purified by columnchromatography to obtain compound 1-3 (27 g, yield 41%).

3) Preparation of Compound 1-4

After introducing compound 1-3 (27.1 g, 65.7 mmol), 2-chloroaniline(13.7 mL, 131.4 mmol), tris(dibenzylidene acetone)dipalladium(0) (1.2 g,1.31 mmol), tri(t-butyl)phosphine (1.5 mL, 3.3 mmol, 50 wt % xylenesolution), sodium t-butoxide (12.5 g, 131.4 mmol), and o-xylene (350 mL)into a reaction vessel, the mixture was under reflux for 3 hours. Thereaction mixture was cooled to room temperature, diluted with ethylacetate, washed with water several times, and dried with anhydrousmagnesium sulfate to remove moisture. The resultant was distilled underreduced pressure, and purified by column chromatography to obtaincompound 1-4 (23.8 g, yield 79%).

4) Preparation of Compound 1-5

After introducing compound 1-4 (23.8 g, 51.9 mmol), palladium(II)acetate(0.6 g, 2.6 mmol), tricyclohexylphosphine tetrafluoroborate (1.9 g, 5.19mmol), cesium carbonate (51 g, 156 mmol), and N,N-dimethylacetylamide(250 mL) into a reaction vessel, the mixture was under reflux for 1hour. The reaction mixture was cooled to room temperature, diluted withethyl acetate, washed with water several times, and dried with anhydrousmagnesium sulfate to remove moisture. The resultant was distilled underreduced pressure, and purified by column chromatography to obtaincompound 1-5 (9.5 g, yield 43%).

5) Preparation of Compound A-6

After introducing compound 1-5 (9.5 g, 22.5 mmol),2-(4-bromophenyl)naphthalene (7.6 g, 27 mmol), copper(I) iodide (2.1 g,11.25 mmol), ethylene diamine (3 mL, 45 mmol), potassium phosphate (10g, 45 mmol), and toluene (120 mL) into a reaction vessel, the mixturewas stirred under reflux at 140° C. for 6 hours. After completion of thereaction, the mixture was washed with distilled water and extracted withethyl acetate. The obtained organic layer was dried with magnesiumsulfate, and the solvent was removed by rotary evaporator. The resultantwas purified by column chromatography to obtain compound A-6 (11.4 g,yield 81%).

MW UV PL M.P A-6 624 307 nm 394 nm 361° C.

[Device Example 1] OLED Using the Organic Electroluminescent Compound ofthe Present Disclosure

OLED was produced using the organic electroluminescent compound of thepresent disclosure as follows. A transparent electrode indium tin oxide(ITO) thin film (10 Ω/sq) on a glass substrate for an organiclight-emitting diode (OLED) (Geomatec) was subjected to an ultrasonicwashing with trichloroethylene, acetone, ethanol, and distilled watersequentially, and was then stored in isopropanol. The ITO substrate wasthen mounted on a substrate holder of a vacuum vapor depositingapparatus.N⁴,N^(4′)-diphenyl-N⁴,N^(4′)-bis(9-phenyl-9H-carbazole-3-yl)-[1,1′-biphenyl]-4,4′-diamine(HI-1) was introduced into a cell of said vacuum vapor depositingapparatus, and then the pressure in the chamber of said apparatus wascontrolled to 10⁻⁶ torr. Thereafter, an electric current was applied tothe cell to evaporate the above introduced material, thereby forming afirst hole injection layer having a thickness of 80 nm on the ITOsubstrate.Dipyrazino[2,3-f:2′,3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile(HI-2) was then introduced into another cell of said vacuum vapordepositing apparatus, and evaporated by applying electric current to thecell, thereby forming a second hole injection layer having a thicknessof 5 nm on the first hole injection layer.N-([1,1′-biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazole-3-yl)phenyl)-9H-fluorene-2-amine (HT-1) was introduced into one cell ofthe vacuum vapor depositing apparatus, and evaporated by applyingelectric current to the cell, thereby forming a first hole transportlayer having a thickness of 10 nm on the second hole injection layer.N,N-di([1,1′-biphenyl]-4-yl)-4′-(9H-carbazole-9-yl)-[1,1′-biphenyl]-4-amine(HT-2) was introduced into another cell of the vacuum vapor depositingapparatus, and evaporated by applying electric current to the cell,thereby forming a second hole transport layer having a thickness of 60nm on the first hole transport layer. Thereafter, compound A-35 wasintroduced into one cell of the vacuum vapor depositing apparatus as ahost, and compound D-96 was introduced into another cell as a dopant.The two materials were evaporated at different rates, so that the dopantwas deposited in a doping amount of 3 wt % based on the total amount ofthe host and dopant to form a light-emitting layer having a thickness of40 nm on the hole transport layer. ET-2 and lithium quinolate (EI-1)were introduced into two cells of the vacuum vapor depositing apparatus,respectively, and evaporated at 1:1 rate to form an electron transportlayer having a thickness of 30 nm on the light-emitting layer. Afterdepositing lithium quinolate as an electron injection layer having athickness of 2 nm, an Al cathode having a thickness of 80 nm was thendeposited by another vacuum vapor deposition apparatus on the electroninjection layer to produce OLED. The produced OLED showed a red emissionhaving a luminance of 1,000 cd/m² at a driving voltage of 3.8V. Theminimum time taken to be reduced to 97% of the luminance at 5,000 nitwas 35 hours.

[Device Example 2] OLED Using the Compound of the Present Disclosure

OLED was produced in the same manner as in Device Example 1, except thatcompound A-53 was used as a host of the light-emitting material, andET-1 was used for an electron transport layer instead of ET-2. Theproduced OLED showed a red emission having a luminance of 1,000 cd/m²,and a current efficiency of 27.3 cd/A at a driving voltage of 3.8 V. Theminimum time taken to be reduced to 97% of the luminance at 5,000 nitwas 42 hours.

[Device Example 3] OLED Using the Compound of the Present Disclosure

OLED was produced using the electroluminescent material of the presentdisclosure as follows. A transparent electrode indium tin oxide (ITO)thin film (10 Ω/sq) on a glass substrate for an organic light-emittingdiode (OLED) (Geomatec) was subjected to an ultrasonic washing withtrichloroethylene, acetone, ethanol and distilled water sequentially,and was then stored in isopropanol. The ITO substrate was then mountedon a substrate holder of a vacuum vapor depositing apparatus.N⁴,N^(4′)-diphenyl-N⁴,N⁴-bis(9-phenyl-9H-carbazole-3-yl)-[1,1′-biphenyl]-4,4′-diamine(HI-1) was introduced into a cell of said vacuum vapor depositingapparatus, and then the pressure in the chamber of said apparatus wascontrolled to 10⁻⁶ torr. Thereafter, an electric current was applied tothe cell to evaporate the above introduced material, thereby forming afirst hole injection layer having a thickness of 80 nm on the ITOsubstrate.Dipyrazino[2,3-f:2′,3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile(HI-2) was then introduced into another cell of said vacuum vapordepositing apparatus, and evaporated by applying electric current to thecell, thereby forming a second hole injection layer having a thicknessof 3 nm on the first hole injection layer.N-([1,1′-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazole-3-yl)phenyl)-9H-fluorene-2-amine(HT-1) was introduced into one cell of the vacuum vapor depositingapparatus, and evaporated by applying electric current to the cell,thereby forming a first hole transport layer having a thickness of 10 nmon the second hole injection layer. Compound A-6 was introduced intoanother cell of the vacuum vapor depositing apparatus, and evaporated byapplying electric current to the cell, thereby forming a second holetransport layer having a thickness of 30 nm on the first hole transportlayer. Thereafter, compound H-1 was introduced into one cell of thevacuum vapor depositing apparatus as a host, and compound D-1 wasintroduced into another cell as a dopant. The two materials wereevaporated at different rates, so that the dopant was deposited in adoping amount of 15 wt % based on the total amount of the host anddopant to form a light-emitting layer having a thickness of 40 nm on thesecond hole transport layer.2,4-bis(9,9-dimethyl-9H-fluoren-2-yl)-6-(naphthalen-2-yl)-1,3,5-triazine(ET-1) and lithium quinolate (EI-1) were introduced into two cells ofthe vacuum vapor depositing apparatus, respectively, and evaporated at5:5 rate to form an electron transport layer having a thickness of 35 nmon the light-emitting layer. After depositing lithium quinolate (EI-1)as an electron injection layer having a thickness of 2 nm, an Al cathodehaving a thickness of 80 nm was then deposited by another vacuum vapordeposition apparatus on the electron injection layer to produce OLED.The produced OLED showed a green emission having a luminance of 1,000cd/m² and a current density of 1.8 mA/cm².

[Device Example 4] OLED Using the Compound of the Present Disclosure

OLED was produced in the same manner as in Device Example 1, except thatthe thickness of the first hole injection layer was 90 nm which is 10 nmthicker than the thickness of 80 nm of Device Example 1; compound A-6was used to form a second hole transport layer having a thickness of 60nm; compound C-2 was introduced into one cell of the vacuum vapordepositing apparatus as a host, and compound D-96 was introduced intoanother cell as a dopant; and the host and the dopant were evaporated atdifferent rates, so that the dopant was deposited in a doping amount of3 wt % based on the total amount of the host and dopant to form alight-emitting layer having a thickness of 40 nm on the second holetransport layer. The produced OLED showed a red emission having aluminance of 1,100 cd/m², and a current density of 4.3 mA/cm².

[Device Example 5] OLED Using the Compound of the Present Disclosure

OLED was produced in the same manner as in Device Example 1, except thatthe thickness of the first hole injection layer was 60 nm which is 20 nmthinner than the thickness of 80 nm of Device Example 1; the thicknessof the first hole transport layer was 20 nm which is 10 nm thicker thanthe thickness of 10 nm of Device Example 1; compound A-6 was used toform a second hole transport layer having a thickness of 5 nm; compoundC-3 was introduced into one cell of the vacuum vapor depositingapparatus as a host, and compound C-4 was introduced into another cellas a dopant; and the host and the dopant were evaporated at differentrates, so that the dopant was deposited in a doping amount of 2 wt %based on the total amount of the host and dopant to form alight-emitting layer having a thickness of 20 nm on the second holetransport layer. The produced OLED showed a blue emission having aluminance of 1,000 cd/m², and a current density of 15.9 mA/cm².

[Comparative Example 1] OLED Using a Conventional OrganicElectroluminescent Material

OLED was produced in the same manner as in Device Example 3, except thatN-([1,1′-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazole-3-yl)phenyl)-9H-fluorene-2-amine(HT-1) was used to form a second hole transport layer having a thicknessof 30 nm. The produced OLED showed a green emission having a luminanceof 9,000 cd/m², and a current density of 21.9 mA/cm².

[Comparative Example 2] OLED Using a Conventional OrganicElectroluminescent Material

OLED was produced in the same manner as in Device Example 4, except thatN-([1,1′-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazole-3-yl)phenyl)-9H-fluorene-2-amine(HT-1) was used to form a second hole transport layer having a thicknessof 60 nm. The produced OLED showed a red emission having a luminance of6,000 cd/m², and a current density of 31.3 mA/cm².

[Comparative Example 3] OLED Using a Conventional OrganicElectroluminescent Material

OLED was produced in the same manner as in Device Example 5, except thatN-([1,1′-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazole-3-yl)phenyl)-9H-fluorene-2-amine(HT-1) was used to form a second hole transport layer having a thicknessof 5 nm. The produced OLED showed a blue emission having a luminance of2,000 cd/m², and a current density of 43.5 mA/cm².

[Comparative Example 4] OLED Using a Conventional OrganicElectroluminescent Material

OLED was produced in the same manner as in Device Example 1, except that4,4′-di(9H-carbazole-9-yl)-1,1′-biphenyl was used as a host oflight-emitting material, and ET-1 was used for an electron transportlayer instead of ET-2. The produced OLED showed a red emission having aluminance of 1,000 cd/m², and a current efficiency of 17.4 cd/A at adriving voltage of 10.3 V. The minimum time taken to be reduced to 97%of the luminance at 5,000 nit was 0 hours (died suddenly).

The working examples above confirm that the compounds for an organicelectronic material of the present disclosure have better luminouscharacteristics than conventional materials. The device employing thecompound for an organic electronic material of the present disclosureshows excellence in luminous characteristics, hole-relatedcharacteristics, and lifespan.

The invention claimed is:
 1. An organic electroluminescent compoundrepresented by formula 1:

wherein X represents —S—; R₁ and R₂ each independently, representhydrogen, deuterium, a halogen, a cyano, a substituted or unsubstituted(C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, asubstituted or unsubstituted (3- to 30-membered)heteroaryl wherein the(3- to 30-membered)heteroaryl is selected from the group consisting offuryl, thiophenyl, pyrrolyl, imidazolyl, pyrazolyl, thiazolyl,thiadiazolyl, isothiazolyl, isoxazolyl, oxazolyl, oxadiazolyl,tetrazinyl, triazolyl, tetrazolyl, furazanyl, pyridyl, pyrazinyl,pyridazinyl, benzofuranyl, benzothiophenyl, isobenzofuranyl,dibenzofuranyl, dibenzothiophenyl, benzoimidazolyl, benzothiazolyl,benzoisothiazolyl, benzoisoxazolyl, benzoxazolyl, isoindolyl, indolyl,indazolyl, benzothiadiazolyl, quinolyl, isoquinolyl, cinnolinyl,quinazolinyl, quinoxalinyl, carbazolyl, phenoxazinyl, phenanthridinyl,benzodioxolyl and dihydroacridinyl, a substituted or unsubstituted(C3-C30)cycloalkyl, a substituted or unsubstituted (C1-C30)alkoxy, asubstituted or unsubstituted tri(C1-C30)alkylsilyl, a substituted orunsubstituted di(C1-C30)alkyl(C6-C30)arylsilyl, a substituted orunsubstituted (C1-C30)alkyldi(C6-C30)arylsilyl, a substituted orunsubstituted tri(C6-C30)arylsilyl, a substituted or unsubstituted mono-or di-(C1-C30)alkylamino, a substituted or unsubstituted mono- ordi-(C6-C30)arylamino, or a substituted or unsubstituted(C1-C30)alkyl(C6-C30)arylamino; or may be linked to an adjacentsubstituent(s) to form a (3- to 30-membered), mono- or polycyclic,alicyclic or aromatic ring whose carbon atom(s) may be replaced with atleast one hetero atom selected from nitrogen, oxygen, and sulfur; thesubstituents on the substituted aryl of R₁ and R₂ are at least oneselected from the group consisting of deuterium, a halogen, a cyano, acarboxy, a nitro, a hydroxyl, a (C1-C30)alkyl, a halo(C1-C30)alkyl, a(C1-C30)alkoxy, a (C1-C30)alkylthio, a (C3-C30)cycloalkyl, a 3- to7-membered heterocycloalkyl, a (C6-C30)aryloxy, a (C6-C30)arylthio, atri(C1-C30)alkylsilyl, a tri(C6-C30)arylsilyl, adi(C1-C30)alkyl(C6-C30)arylsilyl, a (C1-C30)alkyldi(C6-C30)arylsilyl, anamino, a mono- or di-(C1-C30)alkylamino, a mono- ordi-(C6-C30)arylamino, a (C1-C30)alkyl(C6-C30)arylamino, a(C1-C30)alkylcarbonyl, a (C1-C30)alkoxycarbonyl, a (C6-C30)arylcarbonyl,a di(C6-C30)arylboronyl, a di(C1-C30)alkylboronyl, a(C1-C30)alkyl(C6-C30)arylboronyl, a (C6-C30)aryl(C1-C30)alkyl, and a(C1-C30)alkyl(C6-C30)aryl; R₃ to R₆, each independently, representhydrogen, deuterium, a halogen, a cyano, a substituted or unsubstituted(C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, asubstituted or unsubstituted (3- to 30-membered)heteroaryl, asubstituted or unsubstituted (C3-C30)cycloalkyl, a substituted orunsubstituted (C1-C30)alkoxy, a substituted or unsubstitutedtri(C1-C30)alkylsilyl, a substituted or unsubstituteddi(C1-C30)alkyl(C6-C30)arylsilyl, a substituted or unsubstituted(C1-C30)alkyldi(C6-C30)arylsilyl, a substituted or unsubstitutedtri(C6-C30)arylsilyl, a substituted or unsubstituted mono- ordi-(C1-C30)alkylamino, a substituted or unsubstituted mono- or di-(C6-C30)arylamino, or a substituted or unsubstituted(C1-C30)alkyl(C6-C30)arylamino; or may be linked to an adjacentsubstituent(s) to form a (3- to 30-membered), mono- or polycyclic,alicyclic or aromatic ring whose carbon atom(s) may be replaced with atleast one hetero atom selected from nitrogen, oxygen, and sulfur; andthe heteroaryl contains at least one hetero atom selected from B, N, O,S, Si, and P.
 2. The organic electroluminescent compound according toclaim 1, wherein the substituents for the substituted alkyl, thesubstituted heteroaryl, the substituted cycloalkyl, the substitutedalkoxy, the substituted trialkylsilyl, the substituted dialkylarylsilyl,the substituted alkyldiarylsilyl, the substituted triarylsilyl, thesubstituted mono- or di-alkylamino, the substituted mono- ordi-arylamino, the substituted alkylarylamino, and the substituted mono-or polycyclic, alicyclic or aromatic ring of R₁ to R₆, and thesubstituents for the substituted aryl of R₃ to R₆, each independently,are at least one selected from the group consisting of deuterium, ahalogen, a cyano, a carboxy, a nitro, a hydroxy, a (C1-C30)alkyl, ahalo(C1-C30)alkyl, a (C1-C30)alkoxy, a (C1-C30)alkylthio, a(C3-C30)cycloalkyl, a 3- to 7-membered heterocycloalkyl, a(C6-C30)aryloxy, a (C6-C30)arylthio, a 3- to 30-membered heteroarylunsubstituted or substituted with a (C6-C30)aryl or adi(C6-C30)arylamino, a (C6-C30)aryl unsubstituted or substituted with a3- to 30-membered heteroaryl or a di(C6-C30)arylamino, atri(C1-C30)alkylsilyl, a tri(C6-C30)arylsilyl, adi(C1-C30)alkyl(C6-C30)arylsilyl, a (C1-C30)alkyldi(C6-C30)arylsilyl, anamino, a mono- or di-(C1-C30)alkylamino, a mono- ordi-(C6-C30)arylamino, a (C1-C30)alkyl(C6-C30)arylamino, a(C1-C30)alkylcarbonyl, a (C1-C30)alkoxycarbonyl, a (C6-C30)arylcarbonyl,a di(C6-C30)arylboronyl, a di(C1-C30)alkylboronyl, a(C1-C30)alkyl(C6-C30)arylboronyl, a (C6-C30)aryl(C1-C30)alkyl, and a(C1-C30)alkyl(C6-C30)aryl.
 3. The organic electroluminescent compoundaccording to claim 1, wherein the compound of formula 1 is representedby any one of the following formulae 2 to 7:

wherein X, and R₁ to R₆ are as defined in claim
 1. 4. The organicelectroluminescent compound according to claim 1, wherein R₁ and R₂,each independently, represent hydrogen, a substituted or unsubstituted(C6-C30)aryl, or a substituted or unsubstituted 5- to 30-memberedheteroaryl wherein the (3- to 30-membered)heteroaryl is selected fromthe group consisting of furyl, thiophenyl, pyrrolyl, imidazolyl,pyrazolyl, thiazolyl, thiadiazolyl, isothiazolyl, isoxazolyl, oxazolyl,oxadiazolyl, tetrazinyl, triazolyl, tetrazolyl, furazanyl, pyridyl,pyrazinyl, pyridazinyl, benzofuranyl, benzothiophenyl, isobenzofuranyl,dibenzofuranyl, dibenzothiophenyl, benzoimidazolyl, benzothiazolyl,benzoisothiazolyl, benzoisoxazolyl, benzoxazolyl, isoindolyl, indolyl,indazolyl, benzothiadiazolyl, quinolyl, isoquinolyl, cinnolinyl,quinazolinyl, quinoxalinyl, carbazolyl, phenoxazinyl, phenanthridinyl,benzodioxolyl and dihydroacridinyl.
 5. The organic electroluminescentcompound according to claim 1, wherein R₁ represents hydrogen or thegroup represented by formula 8; and R₂ represents hydrogen, or the grouprepresented by formula 9:*-L₁-Ar₁  (8)*-L₂-Ar₂  (9) wherein L₁ and L₂, each independently, represent a singlebond, a substituted or unsubstituted (C6-C30)arylene, or a substitutedor unsubstituted 3- to 30-membered heteroarylene; Ar₁ and Ar₂, eachindependently, represent a substituted or unsubstituted (C6-C30)aryl, ora substituted or unsubstituted 3- to 30-membered heteroaryl wherein the(3- to 30-membered)heteroaryl is selected from the group consisting offuryl, thiophenyl, pyrrolyl, imidazolyl, pyrazolyl, thiazolyl,thiadiazolyl, isothiazolyl, isoxazolyl, oxazolyl, oxadiazolyl,tetrazinyl, triazolyl, tetrazolyl, furazanyl, pyridyl, pyrazinyl,pyridazinyl, benzofuranyl, benzothiophenyl, isobenzofuranyl,dibenzofuranyl, dibenzothiophenyl, benzoimidazolyl, benzothiazolyl,benzoisothiazolyl, benzoisoxazolyl, benzoxazolyl, isoindolyl, indolyl,indazolyl, benzothiadiazolyl, quinolyl, isoquinolyl, cinnolinyl,quinazolinyl, quinoxalinyl, carbazolyl, phenoxazinyl, phenanthridinyl,benzodioxolyl and dihydroacridinyl; and the heteroaryl contains at leastone hetero atom selected from B, N, O, S, Si, and P.
 6. An organicelectroluminescent selected from the group consisting of:


7. An organic electroluminescent device comprising the organicelectroluminescent compound according to claim 1.